VintageBigBlue.org

 

RE: [Losmandy_users] Periodic Rate Too Fast...


Apr 19, 2002

 


----------------------------

#9696 Apr 19, 2002

With all of this worm gear testing, I find that my G-11 runs too fast

by 179.5 arcseconds per hour. For testing I removed this error from

the PE in excel. It did limit my test to 4 or 5 cycles before the

guide star left the tracking box. This is NOT new to the new worm

gear. It seems to happen no matter which of my 5 worms are in the RA

drive. I tried the different rates available on the "Digital Drive":

Sidreal too fast by 179.5 asec/hour

King was even faster (Is that right?)

Lunar was WAY too slow... Solar, didn't bother...



Anyway, Is there an adjustment or some other way to tweak the drive

rate a bit closer to perfect (without using PEC)?



Anybody else see any indications that thier drive is too fast or too

slow?



Any suggestions?



Frank

www.my-spot.com



----------------------------

#9697 Apr 19, 2002

As I have posted previously on the Gemini group (and maybe

this one), my G11/Gemini seems to track at a minimum of

about 60 arcseconds/hour (1 arcsecond per minute) too

fast. I have tried to use PEC to fix this, but my usual

result is that the drift changes (gets faster, gets slower,

reverses direction) but never cancels out, not matter how

well the PEC training seems to go.



Rene says Gemini level 3 will have adjustable tracking rates,

so perhaps that will offer one solution to the problem.



Alan

--- In Losmandy_users@y..., "f_holub" lists@m...> wrote:

> With all of this worm gear testing, I find that my G-11 runs too

fast

> by 179.5 arcseconds per hour. For testing I removed this error from

> the PE in excel. It did limit my test to 4 or 5 cycles before the

> guide star left the tracking box. This is NOT new to the new worm

> gear. It seems to happen no matter which of my 5 worms are in the

RA

> drive. I tried the different rates available on the "Digital

Drive":

> Sidreal too fast by 179.5 asec/hour

> King was even faster (Is that right?)

> Lunar was WAY too slow... Solar, didn't bother...

>

> Anyway, Is there an adjustment or some other way to tweak the drive

> rate a bit closer to perfect (without using PEC)?

>

> Anybody else see any indications that thier drive is too fast or

too

> slow?

>

> Any suggestions?

>

> Frank

> www.my-spot.com



----------------------------

#9698 Apr 19, 2002

Don't bite my head off over this, but isn't that a major flaw.



Sure, I understand the problems that any mechanical device will introduce to

create periodic error. But, I would have thought that the tracking rate

would be better than the numbers you have listed. If your numbers are

correct (and I have no reason to doubt them), that could well explain the

frustration I have with my Gemini controled G11. Periodic error will produce

football shaped stars, but should not create increasingly longer streaks as

exposure increases.



Rene, I hope you're reading these messages because any Gemini user should

not have to pay for upgrades to correct this very serious problem



Wayne ----- Original Message -----

From: "robert_alan_wright" alan@...>

To: Losmandy_users@yahoogroups.com>

Sent: Friday, April 19, 2002 10:01 PM

Subject: [Losmandy_users] Re: Periodic Rate Too Fast...





>

> As I have posted previously on the Gemini group (and maybe

> this one), my G11/Gemini seems to track at a minimum of

> about 60 arcseconds/hour (1 arcsecond per minute) too

> fast. I have tried to use PEC to fix this, but my usual

> result is that the drift changes (gets faster, gets slower,

> reverses direction) but never cancels out, not matter how

> well the PEC training seems to go.

>

> Rene says Gemini level 3 will have adjustable tracking rates,

> so perhaps that will offer one solution to the problem.

>

> Alan

>

> --- In Losmandy_users@y..., "f_holub" lists@m...> wrote:

> > With all of this worm gear testing, I find that my G-11 runs too

> fast

> > by 179.5 arcseconds per hour. For testing I removed this error from

> > the PE in excel. It did limit my test to 4 or 5 cycles before the

> > guide star left the tracking box. This is NOT new to the new worm

> > gear. It seems to happen no matter which of my 5 worms are in the

> RA

> > drive. I tried the different rates available on the "Digital

> Drive":

> > Sidreal too fast by 179.5 asec/hour

> > King was even faster (Is that right?)

> > Lunar was WAY too slow... Solar, didn't bother...

> >

> > Anyway, Is there an adjustment or some other way to tweak the drive

> > rate a bit closer to perfect (without using PEC)?

> >

> > Anybody else see any indications that thier drive is too fast or

> too

> > slow?

> >

> > Any suggestions?

> >

> > Frank

> > www.my-spot.com

>

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com

>

>

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>







----------------------------

#9700 Apr 19, 2002

I just received my G-11/Gemini, so I haven't done any testing yet. I hope

that the reported error in tracking rate is an anomaly, not the norm. If it

turns out to be a problem for others than I agree with the assertion that

this is a bug to be zapped, not an upgrade to be paid for.



chuck

----- Original Message -----

From: "E-Fax" dveterinarian@...>

To: Losmandy_users@yahoogroups.com>

Sent: Friday, April 19, 2002 11:15 PM

Subject: Re: [Losmandy_users] Re: Periodic Rate Too Fast...





> Don't bite my head off over this, but isn't that a major flaw.

>

> Sure, I understand the problems that any mechanical device will introduce

to

> create periodic error. But, I would have thought that the tracking rate

> would be better than the numbers you have listed. If your numbers are

> correct (and I have no reason to doubt them), that could well explain the

> frustration I have with my Gemini controled G11. Periodic error will

produce

> football shaped stars, but should not create increasingly longer streaks

as

> exposure increases.

>

> Rene, I hope you're reading these messages because any Gemini user should

> not have to pay for upgrades to correct this very serious problem

>

> Wayne

> ----- Original Message -----

> From: "robert_alan_wright" alan@...>

> To: Losmandy_users@yahoogroups.com>

> Sent: Friday, April 19, 2002 10:01 PM

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

>

>

> >

> > As I have posted previously on the Gemini group (and maybe

> > this one), my G11/Gemini seems to track at a minimum of

> > about 60 arcseconds/hour (1 arcsecond per minute) too

> > fast. I have tried to use PEC to fix this, but my usual

> > result is that the drift changes (gets faster, gets slower,

> > reverses direction) but never cancels out, not matter how

> > well the PEC training seems to go.

> >

> > Rene says Gemini level 3 will have adjustable tracking rates,

> > so perhaps that will offer one solution to the problem.

> >

> > Alan

> >

> > --- In Losmandy_users@y..., "f_holub" lists@m...> wrote:

> > > With all of this worm gear testing, I find that my G-11 runs too

> > fast

> > > by 179.5 arcseconds per hour. For testing I removed this error from

> > > the PE in excel. It did limit my test to 4 or 5 cycles before the

> > > guide star left the tracking box. This is NOT new to the new worm

> > > gear. It seems to happen no matter which of my 5 worms are in the

> > RA

> > > drive. I tried the different rates available on the "Digital

> > Drive":

> > > Sidreal too fast by 179.5 asec/hour

> > > King was even faster (Is that right?)

> > > Lunar was WAY too slow... Solar, didn't bother...

> > >

> > > Anyway, Is there an adjustment or some other way to tweak the drive

> > > rate a bit closer to perfect (without using PEC)?

> > >

> > > Anybody else see any indications that thier drive is too fast or

> > too

> > > slow?

> > >

> > > Any suggestions?

> > >

> > > Frank

> > > www.my-spot.com

> >

> >

> >

> > To unsubscribe from this group, send an email to:

> > Losmandy_users-unsubscribe@egroups.com

> >

> >

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/

> >

> >

>

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com

>

>

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>



----------------------------

#9702 Apr 19, 2002

----- Original Message -----

From: "E-Fax" dveterinarian@...>

Subject: Re: [Losmandy_users] Re: Periodic Rate Too Fast...





> Don't bite my head off over this, but isn't that a major flaw.

>

> Sure, I understand the problems that any mechanical device will introduce

to

> create periodic error. But, I would have thought that the tracking rate

> would be better than the numbers you have listed. If your numbers are

> correct (and I have no reason to doubt them), that could well explain the

> frustration I have with my Gemini controled G11. Periodic error will

produce

> football shaped stars, but should not create increasingly longer streaks

as

> exposure increases.



Problem is, some folks seem to have no problem with it while others do. If

it were a software problem or a basic design flaw in the Gemini system, then

I would think it would be seen in all systems. Which leaves either quality

control in manufacturing or user error.



Jim Girard

home.teleport.com/~argo



----------------------------

#9706 Apr 20, 2002

Alan, (and others...)

We, at the University of North Texas, experienced the same problem!

One of our undergrads was assigned the task of measuring the PE on a stock

G11/Gemini and upon looking at the graph, we became painfully aware that the

unit was operating faster than sidereal rate. As a result, we have

removed the Gemini

and replaced it with the stock system. Perhaps when the Gemini is

capable of

operating at sidereal rate we'll re-install it!



Regards,

Ron DiIulio

Observatory and Planetarium Manager

University of North Texas



robert_alan_wright wrote:

>As I have posted previously on the Gemini group (and maybe

>this one), my G11/Gemini seems to track at a minimum of

>about 60 arcseconds/hour (1 arcsecond per minute) too

>fast. I have tried to use PEC to fix this, but my usual

>result is that the drift changes (gets faster, gets slower,

>reverses direction) but never cancels out, not matter how

>well the PEC training seems to go.

>

>Rene says Gemini level 3 will have adjustable tracking rates,

>so perhaps that will offer one solution to the problem.

>

>Alan

>

>--- In Losmandy_users@y..., "f_holub" lists@m...> wrote:

>

>>With all of this worm gear testing, I find that my G-11 runs too

>>

>fast

>

>>by 179.5 arcseconds per hour. For testing I removed this error from

>>the PE in excel. It did limit my test to 4 or 5 cycles before the

>>guide star left the tracking box. This is NOT new to the new worm

>>gear. It seems to happen no matter which of my 5 worms are in the

>>

>RA

>

>>drive. I tried the different rates available on the "Digital

>>

>Drive":

>

>>Sidreal too fast by 179.5 asec/hour

>>King was even faster (Is that right?)

>>Lunar was WAY too slow... Solar, didn't bother...

>>

>>Anyway, Is there an adjustment or some other way to tweak the drive

>>rate a bit closer to perfect (without using PEC)?

>>

>>Anybody else see any indications that thier drive is too fast or

>>

>too

>

>>slow?

>>

>>Any suggestions?

>>

>>Frank

>>www.my-spot.com

>>

>

>

>

>To unsubscribe from this group, send an email to:

>Losmandy_users-unsubscribe@egroups.com

>

>

>

>Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>







[Non-text portions of this message have been removed]







----------------------------

#9707 Apr 20, 2002

Jim,

We don't pretend to have the answer to the tracking problem. However, we

advised Scott that we were not interested in "beta testing" this

system.. Since

we have been working under an National Science Foundation grant to test

goto mounts, we've had numerous systems in our hands. The excessive

tracking speed on our Gemini

is not "operator error,", which leaves the other options that you mentioned.

I'm sure that since this is coming to the forefront, Scott and Rene will

make

haste to respond to, and remedy the situation.

Regards,

Ron DiIulo

Observatory and Planetarium Manager

University of North Texas



Jim Girard wrote:

>----- Original Message -----

>From: "E-Fax" dveterinarian@...>

>Subject: Re: [Losmandy_users] Re: Periodic Rate Too Fast...

>

>

>>Don't bite my head off over this, but isn't that a major flaw.

>>

>>Sure, I understand the problems that any mechanical device will introduce

>>

>to

>

>>create periodic error. But, I would have thought that the tracking rate

>>would be better than the numbers you have listed. If your numbers are

>>correct (and I have no reason to doubt them), that could well explain the

>>frustration I have with my Gemini controled G11. Periodic error will

>>

>produce

>

>>football shaped stars, but should not create increasingly longer streaks

>>

>as

>

>>exposure increases.

>>

>

>Problem is, some folks seem to have no problem with it while others do. If

>it were a software problem or a basic design flaw in the Gemini system, then

>I would think it would be seen in all systems. Which leaves either quality

>control in manufacturing or user error.

>

>Jim Girard

>home.teleport.com/~argo

>

>

>

>To unsubscribe from this group, send an email to:

>Losmandy_users-unsubscribe@egroups.com

>

>

>

>Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>







[Non-text portions of this message have been removed]



----------------------------

#9709 Apr 20, 2002

Wayne,



I do not understand, what do you mean with major flaw or

very serious problem?



Frank wrote about the old stepper motor "Digital Drive" system,

not the Gemini.



What Alan writes (0.11 percent deviation from the tracking rate)

shows that the sky moves differently, only at the zenith you have

the exact sidereal rate. King tracking takes care of this.

PEC is not meant to correct for different tracking rates

in the sky caused by refraction.



If you take a look at my website, you'll see that not only bugs

were removed within the Levels, but even new features very included.

The latest L1 software images are available at my website for

free download. L2 and L3 users can get their images from me and

I offer to upgrade their EPROMs at a non-profit fee to let them

take advantage of the latest development.



Ren.

> Don't bite my head off over this, but isn't that a major flaw.

>

> Sure, I understand the problems that any mechanical device will introduce to

> create periodic error. But, I would have thought that the tracking rate

> would be better than the numbers you have listed. If your numbers are

> correct (and I have no reason to doubt them), that could well explain the

> frustration I have with my Gemini controled G11. Periodic error will produce

> football shaped stars, but should not create increasingly longer streaks as

> exposure increases.

>

> Rene, I hope you're reading these messages because any Gemini user should

> not have to pay for upgrades to correct this very serious problem

>

> Wayne

> ----- Original Message -----

> From: "robert_alan_wright" alan@...>

> To: Losmandy_users@yahoogroups.com>

> Sent: Friday, April 19, 2002 10:01 PM

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

>

>

>

>>As I have posted previously on the Gemini group (and maybe

>>this one), my G11/Gemini seems to track at a minimum of

>>about 60 arcseconds/hour (1 arcsecond per minute) too

>>fast. I have tried to use PEC to fix this, but my usual

>>result is that the drift changes (gets faster, gets slower,

>>reverses direction) but never cancels out, not matter how

>>well the PEC training seems to go.

>>

>>Rene says Gemini level 3 will have adjustable tracking rates,

>>so perhaps that will offer one solution to the problem.

>>

>>Alan

>>

>>--- In Losmandy_users@y..., "f_holub" lists@m...> wrote:

>>

>>>With all of this worm gear testing, I find that my G-11 runs too

>>>

>>fast

>>

>>>by 179.5 arcseconds per hour. For testing I removed this error from

>>>the PE in excel. It did limit my test to 4 or 5 cycles before the

>>>guide star left the tracking box. This is NOT new to the new worm

>>>gear. It seems to happen no matter which of my 5 worms are in the

>>>

>>RA

>>

>>>drive. I tried the different rates available on the "Digital

>>>

>>Drive":

>>

>>>Sidreal too fast by 179.5 asec/hour

>>>King was even faster (Is that right?)

>>>Lunar was WAY too slow... Solar, didn't bother...

>>>

>>>Anyway, Is there an adjustment or some other way to tweak the drive

>>>rate a bit closer to perfect (without using PEC)?

>>>

>>>Anybody else see any indications that thier drive is too fast or

>>>

>>too

>>

>>>slow?

>>>

>>>Any suggestions?

>>>

>>>Frank

>>>www.my-spot.com

>>>

>>

>>

>>To unsubscribe from this group, send an email to:

>>Losmandy_users-unsubscribe@egroups.com

>>

>>

>>

>>Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>>

>>

>>

>

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com

>

>

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>

>







----------------------------

#9712 Apr 20, 2002

Ron,



that's most interesting. Alan writes about 60 arcsec

(out of about 54,000 arcsec/hour) for the Gemini, Frank writes

about 179.5 arcsec/hour for the stock "Digital Drive" system,

that's three times the amount of the Gemini, and you replaced

the Gemini with the stepper system because of it's tracking?



Could you please elaborate about the test setup used, what you

expected and the results you've got?



We had Gemini's tracking tested from California to Florida,

in Europe, in Australia. Lot's of people spent a lot of their

time for pretty boring tracking rate tests. Many Gemini units

were involved. No tracking rate deviation was found.



60 arcsec per hour are 0.11 percent of the tracking rate.

That's too much to be caused by hardware (far more than the

quartz' tolerancy is), but smaller than the effects caused by the

atmosphere, and much smaller than mechanical effects like slippage,

flexure or mirror flop.



Ren.

> Alan, (and others...)

> We, at the University of North Texas, experienced the same problem!

> One of our undergrads was assigned the task of measuring the PE on a stock

> G11/Gemini and upon looking at the graph, we became painfully aware that the

> unit was operating faster than sidereal rate. As a result, we have

> removed the Gemini

> and replaced it with the stock system. Perhaps when the Gemini is

> capable of

> operating at sidereal rate we'll re-install it!

>

> Regards,

> Ron DiIulio

> Observatory and Planetarium Manager

> University of North Texas

>

> robert_alan_wright wrote:

>

>

>>As I have posted previously on the Gemini group (and maybe

>>this one), my G11/Gemini seems to track at a minimum of

>>about 60 arcseconds/hour (1 arcsecond per minute) too

>>fast. I have tried to use PEC to fix this, but my usual

>>result is that the drift changes (gets faster, gets slower,

>>reverses direction) but never cancels out, not matter how

>>well the PEC training seems to go.

>>

>>Rene says Gemini level 3 will have adjustable tracking rates,

>>so perhaps that will offer one solution to the problem.

>>

>>Alan

>>

>>--- In Losmandy_users@y..., "f_holub" lists@m...> wrote:

>>

>>

>>>With all of this worm gear testing, I find that my G-11 runs too

>>>

>>>

>>fast

>>

>>

>>>by 179.5 arcseconds per hour. For testing I removed this error from

>>>the PE in excel. It did limit my test to 4 or 5 cycles before the

>>>guide star left the tracking box. This is NOT new to the new worm

>>>gear. It seems to happen no matter which of my 5 worms are in the

>>>

>>>

>>RA

>>

>>

>>>drive. I tried the different rates available on the "Digital

>>>

>>>

>>Drive":

>>

>>

>>>Sidreal too fast by 179.5 asec/hour

>>>King was even faster (Is that right?)

>>>Lunar was WAY too slow... Solar, didn't bother...

>>>

>>>Anyway, Is there an adjustment or some other way to tweak the drive

>>>rate a bit closer to perfect (without using PEC)?

>>>

>>>Anybody else see any indications that thier drive is too fast or

>>>

>>>

>>too

>>

>>

>>>slow?

>>>

>>>Any suggestions?

>>>

>>>Frank

>>>www.my-spot.com

>>>

>>>

>>

>>

>>To unsubscribe from this group, send an email to:

>>Losmandy_users-unsubscribe@egroups.com

>>

>>

>>

>>Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>>

>>

>>

>>

>

>

>

> [Non-text portions of this message have been removed]

>

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com

>

>

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>

>



----------------------------

#9720 Apr 20, 2002

--- In Losmandy_users@y..., Rene Goerlich Rene@D...> wrote: >

> What Alan writes (0.11 percent deviation from the tracking rate)

> shows that the sky moves differently, only at the zenith you have

> the exact sidereal rate. King tracking takes care of this.

> PEC is not meant to correct for different tracking rates

> in the sky caused by refraction.



This is not correct for at least my case. My tracking is too

fast *at the meridian*. The data posted to the file section

of this group (for the new worm threads) shows the amount of

RA drift I get near the meridian. The graph, in particular,

makes it obvious. It doesn't seem as though the King rate

should help, since King and Sidereal should be the same near

the meridian. Correct? To the limited extent that I have tried

the (on-adaptive) King rate, it did not help at all.



For me this is not too much of a problem. If I could guide at

all with my mount, I could guide this small drift out. However,

with many people reporting the same problem to differing degrees,

including people with vastly more expertise than myself, it is

annoying that you are so defensive about this. If you want to

claim (as Scott Losmandy said to me), that this is within the

manufacturting limits of the product, then do so, and let the

chips fall where they may.



With the greatly improved worm gears that Losmandy will soon

apparently be shipping, this problem will become much more

glaring. When my PE was greater than 30 arcseconds, there was

no way I could notice this problem. But I saw it immediately

after the new worm was installed.

> If you take a look at my website, you'll see that not only bugs

> were removed within the Levels, but even new features very included.

> The latest L1 software images are available at my website for

> free download. L2 and L3 users can get their images from me and

> I offer to upgrade their EPROMs at a non-profit fee to let them

> take advantage of the latest development.



I hope you are not implying that known bugs are left in level 1

in order to induce people to upgrade. For a $1500 system, holding

out for a few more bucks to get bug fixes is practically criminal.

By the standards of the US software industry, you would have to

give away the upgrades if that was the only means you had to fix

known bugs.



It amazes me that so many of the astronomy products I buy

have a mix of astoundingly good qualities and designs mixed

with egregious and unnecessary flaws. For example, my G11/Gemini

is generally a beautiful and finely crafted mount, yet does not

track well enough to make CCD images. Apparently the market is

not large enough (or is too forgiving) for appropriate pressures

to be applied to the producers. Some of the companies I have bought

from, however, adhere to higher standards than others, and I will

definitely channel my future expenditures in those directions, and

warn people away from products I have had trouble with. I only wish

I had heeded some of the warnings I received before I made certain

purchases.



Alan







----------------------------

#9721 Apr 20, 2002

Alan,



Try to step back and chill out a bit. As you may have seen in my emails

to Rene, we have also found some problems with the Gemini. However, I

have found that even though we've had two units totally fail, the

problems were resolved to our satisfaction. For the past year, I've

repeatedly said that I didn't want to be a "beta tester" for this

product. Well....I've had to...that's the price I've paid for purchasing

a "cutting edge" product. I hope you will reconsider your position and

let's try and work out these problems together, as a virtual team from

around the world!



Now the problem that some of us notice concerning RA tracking

speed---please note that Rene said "zenith", not "meridian". There is an

variation in the angular motions at the meridian depending on the dec of

the tracked object. In scientific fairness to Rene, I emailed him and

offered to send one of my students back to the field to guarantee that

our results took altitude and azimuth positions into consideration.

I hope you will do the same.

Regards,

Ron DiIulio

Observatory and Planetarium Manager

University of North Texas



robert_alan_wright wrote:

>--- In Losmandy_users@y..., Rene Goerlich Rene@D...> wrote:

>

>>What Alan writes (0.11 percent deviation from the tracking rate)

>>shows that the sky moves differently, only at the zenith you have

>>the exact sidereal rate. King tracking takes care of this.

>>PEC is not meant to correct for different tracking rates

>>in the sky caused by refraction.

>>

>

>This is not correct for at least my case. My tracking is too

>fast *at the meridian*. The data posted to the file section

>of this group (for the new worm threads) shows the amount of

>RA drift I get near the meridian. The graph, in particular,

>makes it obvious. It doesn't seem as though the King rate

>should help, since King and Sidereal should be the same near

>the meridian. Correct? To the limited extent that I have tried

>the (on-adaptive) King rate, it did not help at all.

>

>For me this is not too much of a problem. If I could guide at

>all with my mount, I could guide this small drift out. However,

>with many people reporting the same problem to differing degrees,

>including people with vastly more expertise than myself, it is

>annoying that you are so defensive about this. If you want to

>claim (as Scott Losmandy said to me), that this is within the

>manufacturting limits of the product, then do so, and let the

>chips fall where they may.

>

>With the greatly improved worm gears that Losmandy will soon

>apparently be shipping, this problem will become much more

>glaring. When my PE was greater than 30 arcseconds, there was

>no way I could notice this problem. But I saw it immediately

>after the new worm was installed.

>

>

>>If you take a look at my website, you'll see that not only bugs

>>were removed within the Levels, but even new features very included.

>>The latest L1 software images are available at my website for

>>free download. L2 and L3 users can get their images from me and

>>I offer to upgrade their EPROMs at a non-profit fee to let them

>>take advantage of the latest development.

>>

>

>I hope you are not implying that known bugs are left in level 1

>in order to induce people to upgrade. For a $1500 system, holding

>out for a few more bucks to get bug fixes is practically criminal.

>By the standards of the US software industry, you would have to

>give away the upgrades if that was the only means you had to fix

>known bugs.

>

>It amazes me that so many of the astronomy products I buy

>have a mix of astoundingly good qualities and designs mixed

>with egregious and unnecessary flaws. For example, my G11/Gemini

>is generally a beautiful and finely crafted mount, yet does not

>track well enough to make CCD images. Apparently the market is

>not large enough (or is too forgiving) for appropriate pressures

>to be applied to the producers. Some of the companies I have bought

>from, however, adhere to higher standards than others, and I will

>definitely channel my future expenditures in those directions, and

>warn people away from products I have had trouble with. I only wish

>I had heeded some of the warnings I received before I made certain

>purchases.

>

>Alan

>

>

>

>

>To unsubscribe from this group, send an email to:

>Losmandy_users-unsubscribe@egroups.com

>

>

>

>Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>







[Non-text portions of this message have been removed]



----------------------------

#9722 Apr 20, 2002

>What Alan writes (0.11 percent deviation from the tracking rate)

>>shows that the sky moves differently, only at the zenith you have

>>the exact sidereal rate. King tracking takes care of this.

>>PEC is not meant to correct for different tracking rates

>>in the sky caused by refraction.

>

> This is not correct for at least my case. My tracking is too

> fast *at the meridian*. The data posted to the file section

> of this group (for the new worm threads) shows the amount of

> RA drift I get near the meridian. The graph, in particular,

> makes it obvious. It doesn't seem as though the King rate

> should help, since King and Sidereal should be the same near

> the meridian. Correct? To the limited extent that I have tried

> the (on-adaptive) King rate, it did not help at all.





That's very strange, the non-adaptive King rate should have cut

the error down to half of the value at maximum. It IS slower.



And no, since you are not observing from the north or the south

pole, King and Sidereal will not be the same. Would have been nice

if you would have tested the King rate.

> For me this is not too much of a problem. If I could guide at

> all with my mount, I could guide this small drift out. However,

> with many people reporting the same problem to differing degrees,

> including people with vastly more expertise than myself, it is

> annoying that you are so defensive about this. If you want to

> claim (as Scott Losmandy said to me), that this is within the

> manufacturting limits of the product, then do so, and let the

> chips fall where they may.





What do you expect me to do? Should I replace the valid timer

values by arbitrary ones to slow down the tracking?

> With the greatly improved worm gears that Losmandy will soon

> apparently be shipping, this problem will become much more

> glaring. When my PE was greater than 30 arcseconds, there was

> no way I could notice this problem. But I saw it immediately

> after the new worm was installed.





>>If you take a look at my website, you'll see that not only bugs

>>were removed within the Levels, but even new features very included.

>>The latest L1 software images are available at my website for

>>free download. L2 and L3 users can get their images from me and

>>I offer to upgrade their EPROMs at a non-profit fee to let them

>>take advantage of the latest development.

>>

>

> I hope you are not implying that known bugs are left in level 1

> in order to induce people to upgrade. For a $1500 system, holding

> out for a few more bucks to get bug fixes is practically criminal.

> By the standards of the US software industry, you would have to

> give away the upgrades if that was the only means you had to fix

> known bugs.





Criminal? For applying the correct values? Thank you.

My English may be bad, but most of the people on this group should

know that I was very responsive to any problem and all problems

were solved.

> It amazes me that so many of the astronomy products I buy

> have a mix of astoundingly good qualities and designs mixed

> with egregious and unnecessary flaws. For example, my G11/Gemini

> is generally a beautiful and finely crafted mount, yet does not

> track well enough to make CCD images. Apparently the market is

> not large enough (or is too forgiving) for appropriate pressures

> to be applied to the producers. Some of the companies I have bought

> from, however, adhere to higher standards than others, and I will

> definitely channel my future expenditures in those directions, and

> warn people away from products I have had trouble with. I only wish

> I had heeded some of the warnings I received before I made certain

> purchases.





Thank you again. I'll leave the decisions about this statement

to the group.







----------------------------

#9723 Apr 20, 2002

Hello to all.



My first response is to state that it would be more productive if the

users here would remember that we are humans, and we too have

feelings. If you think there are problems, the only way we could

address them is with accurate technical data. This includes equipment

used, sky conditions, graphs in arc seconds (not pixels) and the

ground surface. Then we can assess the issues and can come up with

possible solutions.



If I were to start addressing users as "another problem user that

does not know what he is doing" I don't think this would be taken

lightly. Clearly an inappropriate statement.



Now to the issue;



Alan wrote:

As I have posted previously on the Gemini group (and maybe > this one), my G11/Gemini seems to track at a minimum

of > about 60 arcseconds/hour (1 arcsecond per minute)

too > fast. I have tried to use PEC to fix this, but my

usual > result is that the drift changes (gets faster, gets

slower, > reverses direction) but never cancels out, not

matter how

. well the PEC training seems to go.





Frank wrote:

With all of this worm gear testing, I find that my G-11 runs too > fast

> > by 179.5 arcseconds per hour. For testing I

removed this error from > > the PE in excel. It did limit my test to 4 or 5

cycles before the > > guide star left the tracking box. This is NOT new

to the new worm > > gear. It seems to happen no matter which of my 5

worms are in the > RA

> > drive. I tried the different rates available on

the "Digital

. Drive":





Considering the fact that these are two different drive systems, one

being the stepper and one being the servo and they both have a

tracking speed problem, and one even going backwards, I think we need

to look somewhere else for the causes.

My question is were the above tests run for a full hour or are they a

calculated hour?





Thank you,

Scott



----------------------------

#9724 Apr 20, 2002

That crazy carpenter from the backwoods of Maine once said,

"Some people you just don't want to build a house for, because

it's just not worth the trouble." I wonder what he meant by

that :)



On another note. Where the heck is Greg Nowell? Greg if you are

out there, then what's up?



Regards,

--- In Losmandy_users@y..., Rene Goerlich Rene@D...> wrote:

> >>What Alan writes (0.11 percent deviation from the tracking rate)

> >>shows that the sky moves differently, only at the zenith you have

> >>the exact sidereal rate. King tracking takes care of this.

> >>PEC is not meant to correct for different tracking rates

> >>in the sky caused by refraction.

> >

> > This is not correct for at least my case. My tracking is too

> > fast *at the meridian*. The data posted to the file section

> > of this group (for the new worm threads) shows the amount of

> > RA drift I get near the meridian. The graph, in particular,

> > makes it obvious. It doesn't seem as though the King rate

> > should help, since King and Sidereal should be the same near

> > the meridian. Correct? To the limited extent that I have tried

> > the (on-adaptive) King rate, it did not help at all.

>

>

> That's very strange, the non-adaptive King rate should have cut

> the error down to half of the value at maximum. It IS slower.

>

> And no, since you are not observing from the north or the south

> pole, King and Sidereal will not be the same. Would have been nice

> if you would have tested the King rate.

>

> > For me this is not too much of a problem. If I could guide at

> > all with my mount, I could guide this small drift out. However,

> > with many people reporting the same problem to differing degrees,

> > including people with vastly more expertise than myself, it is

> > annoying that you are so defensive about this. If you want to

> > claim (as Scott Losmandy said to me), that this is within the

> > manufacturting limits of the product, then do so, and let the

> > chips fall where they may.

>

>

> What do you expect me to do? Should I replace the valid timer

> values by arbitrary ones to slow down the tracking?

>

> > With the greatly improved worm gears that Losmandy will soon

> > apparently be shipping, this problem will become much more

> > glaring. When my PE was greater than 30 arcseconds, there was

> > no way I could notice this problem. But I saw it immediately

> > after the new worm was installed.

>

>

> >>If you take a look at my website, you'll see that not only bugs

> >>were removed within the Levels, but even new features very

included.

> >>The latest L1 software images are available at my website for

> >>free download. L2 and L3 users can get their images from me and

> >>I offer to upgrade their EPROMs at a non-profit fee to let them

> >>take advantage of the latest development.

> >>

> >

> > I hope you are not implying that known bugs are left in level 1

> > in order to induce people to upgrade. For a $1500 system, holding

> > out for a few more bucks to get bug fixes is practically

criminal.

> > By the standards of the US software industry, you would have to

> > give away the upgrades if that was the only means you had to fix

> > known bugs.

>

>

> Criminal? For applying the correct values? Thank you.

> My English may be bad, but most of the people on this group should

> know that I was very responsive to any problem and all problems

> were solved.

>

> > It amazes me that so many of the astronomy products I buy

> > have a mix of astoundingly good qualities and designs mixed

> > with egregious and unnecessary flaws. For example, my G11/Gemini

> > is generally a beautiful and finely crafted mount, yet does not

> > track well enough to make CCD images. Apparently the market is

> > not large enough (or is too forgiving) for appropriate pressures

> > to be applied to the producers. Some of the companies I have

bought

> > from, however, adhere to higher standards than others, and I will

> > definitely channel my future expenditures in those directions,

and

> > warn people away from products I have had trouble with. I only

wish

> > I had heeded some of the warnings I received before I made

certain

> > purchases.

>

>

> Thank you again. I'll leave the decisions about this statement

> to the group.







----------------------------

#9725 Apr 20, 2002

Alan,



I think that do Scott and Rene' and injustice by what you are saying and the

way you are saying it. Let's step back for a moment and look at the data

your conclusions are based on. If you are basing your statement that the RA

speed is off on the fact that there is drift in your track logs, I think you

may be misinterpreting what you are seeing.



I have been looking at some track logs that I have run and I would like the

reasoned wisdom of group review on my conclusions. Here is what I am seeing

that has me thinking. I notice a positional drift in RA that appears to be

proportional to the drift in Dec due to imprecise polar alignment. If I was

dead on the meridian, then I guess I could expect the Dec drift to be only

in Y. If I am away from the meridian, I seem to be seeing an X component to

the drift. I do not believe this is a rate error. I have been pulling this

drift out of the PE data I have been using, but do not fully understand what

I am seeing. Thoughts?



Marty



----- Original Message -----

From: "robert_alan_wright" alan@...>

To: Losmandy_users@yahoogroups.com>

Sent: Saturday, April 20, 2002 1:06 PM

Subject: [Losmandy_users] Re: Periodic Rate Too Fast...





> --- In Losmandy_users@y..., Rene Goerlich Rene@D...> wrote:

> >

> > What Alan writes (0.11 percent deviation from the tracking rate)

> > shows that the sky moves differently, only at the zenith you have

> > the exact sidereal rate. King tracking takes care of this.

> > PEC is not meant to correct for different tracking rates

> > in the sky caused by refraction.

>

> This is not correct for at least my case. My tracking is too

> fast *at the meridian*. The data posted to the file section

> of this group (for the new worm threads) shows the amount of

> RA drift I get near the meridian. The graph, in particular,

> makes it obvious. It doesn't seem as though the King rate

> should help, since King and Sidereal should be the same near

> the meridian. Correct? To the limited extent that I have tried

> the (on-adaptive) King rate, it did not help at all.

>

> For me this is not too much of a problem. If I could guide at

> all with my mount, I could guide this small drift out. However,

> with many people reporting the same problem to differing degrees,

> including people with vastly more expertise than myself, it is

> annoying that you are so defensive about this. If you want to

> claim (as Scott Losmandy said to me), that this is within the

> manufacturting limits of the product, then do so, and let the

> chips fall where they may.

>

> With the greatly improved worm gears that Losmandy will soon

> apparently be shipping, this problem will become much more

> glaring. When my PE was greater than 30 arcseconds, there was

> no way I could notice this problem. But I saw it immediately

> after the new worm was installed.

>

> > If you take a look at my website, you'll see that not only bugs

> > were removed within the Levels, but even new features very included.

> > The latest L1 software images are available at my website for

> > free download. L2 and L3 users can get their images from me and

> > I offer to upgrade their EPROMs at a non-profit fee to let them

> > take advantage of the latest development.

>

> I hope you are not implying that known bugs are left in level 1

> in order to induce people to upgrade. For a $1500 system, holding

> out for a few more bucks to get bug fixes is practically criminal.

> By the standards of the US software industry, you would have to

> give away the upgrades if that was the only means you had to fix

> known bugs.

>

> It amazes me that so many of the astronomy products I buy

> have a mix of astoundingly good qualities and designs mixed

> with egregious and unnecessary flaws. For example, my G11/Gemini

> is generally a beautiful and finely crafted mount, yet does not

> track well enough to make CCD images. Apparently the market is

> not large enough (or is too forgiving) for appropriate pressures

> to be applied to the producers. Some of the companies I have bought

> from, however, adhere to higher standards than others, and I will

> definitely channel my future expenditures in those directions, and

> warn people away from products I have had trouble with. I only wish

> I had heeded some of the warnings I received before I made certain

> purchases.

>

> Alan

>

>

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@egroups.com

>

>

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>



----------------------------

#9726 Apr 20, 2002

Don't misreasd my post. My problem is not specifically with

the tracking rate error, as I can easily live with that. My

problem is with vendors who get defensive about problems

with their product instead of working with the customer to

resolve them. Denying the problems are real does not help.

Identifying user errors, if there are any, does help.



I did not bring up the thread about the tracking rate problem.

I just responded to someone else who inquired as to whether

others had seen it. Some time back I posted a note about it

on the Gemini group. Several people responded to me publically

and privately to confirm seeing the same problem. Rene offered

some ideas about the cause, but once these were safely ruled

out he simply repeated the previous stuff and was very

defensive (much as he is now).



Rene's attitude is bizarre. This is a product, not a science

experiment. Only if the algorithms successfully drive the

mechanical mount is it a good product. If he only used two

lines of code to do the sidereal rate, then perhaps he needs

to upgrade that to a table lookup that works better in most

parts of the sky. But no, his science is perfect so the

product cannot possibly fail.



Right now I have a list of about 10 other problems with

the Gemini that I would like to discuss. But the climate in

these groups has discouraged me from doing that. I'd rather

just get rid of this product and use something else where I

can get the help I need (and maybe even get a product that

works).



Look for a used G11/Gemini on Astromart in the near future.



Alan

--- In Losmandy_users@y..., ronkeys@s... wrote:

> Alan,

>

> Try to step back and chill out a bit. As you may have seen in my

emails

> to Rene, we have also found some problems with the Gemini.

However, I

> have found that even though we've had two units totally fail, the

> problems were resolved to our satisfaction. For the past year,

I've

> repeatedly said that I didn't want to be a "beta tester" for this

> product. Well....I've had to...that's the price I've paid for

purchasing

> a "cutting edge" product. I hope you will reconsider your position

and

> let's try and work out these problems together, as a virtual team

from

> around the world!

>

> Now the problem that some of us notice concerning RA tracking

> speed---please note that Rene said "zenith", not "meridian". There

is an

> variation in the angular motions at the meridian depending on the

dec of

> the tracked object. In scientific fairness to Rene, I emailed him

and

> offered to send one of my students back to the field to guarantee

that

> our results took altitude and azimuth positions into consideration.

> I hope you will do the same.

> Regards,

> Ron DiIulio

> Observatory and Planetarium Manager

> University of North Texas

>

> robert_alan_wright wrote:

>

> >--- In Losmandy_users@y..., Rene Goerlich Rene@D...> wrote:

> >

> >>What Alan writes (0.11 percent deviation from the tracking rate)

> >>shows that the sky moves differently, only at the zenith you have

> >>the exact sidereal rate. King tracking takes care of this.

> >>PEC is not meant to correct for different tracking rates

> >>in the sky caused by refraction.

> >>

> >

> >This is not correct for at least my case. My tracking is too

> >fast *at the meridian*. The data posted to the file section

> >of this group (for the new worm threads) shows the amount of

> >RA drift I get near the meridian. The graph, in particular,

> >makes it obvious. It doesn't seem as though the King rate

> >should help, since King and Sidereal should be the same near

> >the meridian. Correct? To the limited extent that I have tried

> >the (on-adaptive) King rate, it did not help at all.

> >

> >For me this is not too much of a problem. If I could guide at

> >all with my mount, I could guide this small drift out. However,

> >with many people reporting the same problem to differing degrees,

> >including people with vastly more expertise than myself, it is

> >annoying that you are so defensive about this. If you want to

> >claim (as Scott Losmandy said to me), that this is within the

> >manufacturting limits of the product, then do so, and let the

> >chips fall where they may.

> >

> >With the greatly improved worm gears that Losmandy will soon

> >apparently be shipping, this problem will become much more

> >glaring. When my PE was greater than 30 arcseconds, there was

> >no way I could notice this problem. But I saw it immediately

> >after the new worm was installed.

> >

> >

> >>If you take a look at my website, you'll see that not only bugs

> >>were removed within the Levels, but even new features very

included.

> >>The latest L1 software images are available at my website for

> >>free download. L2 and L3 users can get their images from me and

> >>I offer to upgrade their EPROMs at a non-profit fee to let them

> >>take advantage of the latest development.

> >>

> >

> >I hope you are not implying that known bugs are left in level 1

> >in order to induce people to upgrade. For a $1500 system, holding

> >out for a few more bucks to get bug fixes is practically criminal.

> >By the standards of the US software industry, you would have to

> >give away the upgrades if that was the only means you had to fix

> >known bugs.

> >

> >It amazes me that so many of the astronomy products I buy

> >have a mix of astoundingly good qualities and designs mixed

> >with egregious and unnecessary flaws. For example, my G11/Gemini

> >is generally a beautiful and finely crafted mount, yet does not

> >track well enough to make CCD images. Apparently the market is

> >not large enough (or is too forgiving) for appropriate pressures

> >to be applied to the producers. Some of the companies I have

bought

> >from, however, adhere to higher standards than others, and I will

> >definitely channel my future expenditures in those directions, and

> >warn people away from products I have had trouble with. I only

wish

> >I had heeded some of the warnings I received before I made certain

> >purchases.

> >

> >Alan

> >

> >

> >

> >

> >To unsubscribe from this group, send an email to:

> >Losmandy_users-unsubscribe@e...

> >

> >

> >

> >Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/

> >

> >

> >

>

>

>

> [Non-text portions of this message have been removed]







----------------------------

#9727 Apr 20, 2002

--- In Losmandy_users@y..., Rene Goerlich Rene@D...> wrote: > > This is not correct for at least my case. My tracking is too

> > fast *at the meridian*. The data posted to the file section

> > of this group (for the new worm threads) shows the amount of

> > RA drift I get near the meridian. The graph, in particular,

> > makes it obvious. It doesn't seem as though the King rate

> > should help, since King and Sidereal should be the same near

> > the meridian. Correct? To the limited extent that I have tried

> > the (on-adaptive) King rate, it did not help at all.

>

>

> That's very strange, the non-adaptive King rate should have cut

> the error down to half of the value at maximum. It IS slower.

>

> And no, since you are not observing from the north or the south

> pole, King and Sidereal will not be the same. Would have been nice

> if you would have tested the King rate.



When I tested it, the mount tracking became unstable and I lost

the object several times, so I gave up. Then I read that others

with the fast sidereal rate did not think the King rate helped,

so I have not bothered to try again. Perhaps I will, but based

on your recent responses I am not at all encouraged to use your

product, let alone test it for you. You still have never responded

as to why the tracking goes crazy when I switch rates.

> What do you expect me to do? Should I replace the valid timer

> values by arbitrary ones to slow down the tracking?



If the result is inconsistent among mounts, then no. If this

is just a manufacturing flaw of my mount, just say so and I

will go away. If you are capable of getting all of these mounts

to track correctly, then whatever software fix is required to

achieve this is desirable to me.

> Criminal? For applying the correct values? Thank you.



I retract the use of the word "criminal", as it evidently

sounds stronger to you than it means in American vernacular.



Here is some english and business 101: correct is what is

right for the customer, which is generally what makes the

product work correctly. I developed technical products

for 25 years, and I had my share of disputes with customers

as to what is "correct", so I know your point of view. Being

on the other side now, however, I get no benefit from your

defensive attitude, and don't appreciate it.

> My English may be bad, but most of the people on this group should

> know that I was very responsive to any problem and all problems

> were solved.



Perhaps so, but my experience has been different. And it is

a gross exaggeration to claim that *all* problems are solved.



Alan



----------------------------

#9728 Apr 20, 2002

--- In Losmandy_users@y..., "losmandy" scott@l...> wrote: > Hello to all.

>

> My first response is to state that it would be more productive if

the > users here would remember that we are humans, and we too have

> feelings. If you think there are problems, the only way we could

> address them is with accurate technical data. This includes

equipment > used, sky conditions, graphs in arc seconds (not pixels) and the

> ground surface. Then we can assess the issues and can come up with

> possible solutions.

>

> If I were to start addressing users as "another problem user that

> does not know what he is doing" I don't think this would be taken

> lightly. Clearly an inappropriate statement.

>

> Now to the issue;

>

> Alan wrote:

> As I have posted previously on the Gemini group (and maybe

> > this one), my G11/Gemini seems to track at a

minimum > of

> > about 60 arcseconds/hour (1 arcsecond per

minute) > too

> > fast. I have tried to use PEC to fix this, but

my > usual

> > result is that the drift changes (gets faster,

gets > slower,

> > reverses direction) but never cancels out, not

> matter how

> . well the PEC training seems to go.

>

>

> Frank wrote:

> With all of this worm gear testing, I find that my G-11 runs too

> > fast

> > > by 179.5 arcseconds per hour. For testing I

> removed this error from

> > > the PE in excel. It did limit my test to 4 or

5 > cycles before the

> > > guide star left the tracking box. This is NOT

new > to the new worm

> > > gear. It seems to happen no matter which of my

5 > worms are in the

> > RA

> > > drive. I tried the different rates available

on > the "Digital

> . Drive":

>

>

> Considering the fact that these are two different drive systems,

one > being the stepper and one being the servo and they both have a

> tracking speed problem, and one even going backwards, I think we

need > to look somewhere else for the causes.

> My question is were the above tests run for a full hour or are

they a > calculated hour?



Scott,



I appreciate your calm, reasoned response. However, I have stated

that I don't really care about this particular problem, so I don't

want to drag it out further. I reported it to you when I first got

my new gears, as I was curious if these were related. Enough other

people (all with much greater expertise than mine), have reported

similar things, so I will leave it to them to work out the causes

if they are so motivated. Hopefully they will publish their

findings in case it might benefit the rest of us.



I will be satisifed with this mount for a while if I can get

it to guide well enough for CCD photos. I would much rather

hear from you about ways to improve my guiding than about

sidereal rates.



Alan







----------------------------

#9729 Apr 20, 2002

Marty,



I believe that you will see some "drift" in RA (i.e. the whole

sinusoidal graph seems to be moving up or down over time)

which is indeed due to your polar misalignment and NOT any

sort of drive error. I'm assuming of course that you are not

sending corrections to the drive. Just monitoring a guide

star in order to try and characterize your PE and or polar

misalignment.



If you get the CCD chip's X and Y axes aligned well with the

RA and DEC axis, then the effects of this are minimized.



However, it will always be there to some degree since we can

never be perfectly polar aligned and we can never perfectly

align the CCD chip's X and Y axes to the mount's RA and DEC

axis either.



This is one of the reasons that I try to focus on the difference

between individual measurements more than the absolute value of

the measurements. Taking the difference between measurements

cancels out this "drift" effect (both measurements drifted by

about the same amount while data was being gathered) and forces

you to consider what is really important anyway. That is how

fast is the PE changing, not what is its absolute magnitude.



I've done some formal statistical analysis on these differences,

and they do appear to be truly random, despite the fact that there

is a well-known mathematical model that explains the PE of a

worm/spur gear assembly.



Since they are random maybe we could start to do some t-tests

and or F-tests to see if the differences between peoples data

sets are "real" or just due to random deviation.



I think it is important too, to sample as fast as you can when

gathering this kind of data. Even when setting exposures to 1

second, gathering a sample every 3 seconds or so is a challenge.



I saw that some people had their exposure set to 5 seconds or

longer. This is too long I think, and may be introducing "false"

signatures due to "aliasing".



To understand what I mean by aliasing think of the following.

Imagine a sinusoidal signal that completes 1000 cycles per

second. If I now gather data from that signal at a rate of

a 1000 times per second what do I get? The same value over

and over; no matter when I started sampling. Because I chose

a poor sampling rate (too slow) the signal that completes

1000 cycles per second, looks like it is a constant value

to me. I wonder if some of this kind of stuff could not be

going on too.



The 1000 cycles per second signal was "aliased" to a 0 cycles

per second signal, because I sampled it too slowly.



It is probably just common sense, but to get the most accurate

picture sample as fast as you can.



Regards,

--- In Losmandy_users@y..., "Marty Niemi" mniemi000@a...> wrote:

> Alan,

>

> I think that do Scott and Rene' and injustice by what you are

saying and the

> way you are saying it. Let's step back for a moment and look at

the data

> your conclusions are based on. If you are basing your statement

that the RA

> speed is off on the fact that there is drift in your track logs, I

think you

> may be misinterpreting what you are seeing.

>

> I have been looking at some track logs that I have run and I would

like the

> reasoned wisdom of group review on my conclusions. Here is what I

am seeing

> that has me thinking. I notice a positional drift in RA that

appears to be

> proportional to the drift in Dec due to imprecise polar

alignment. If I was

> dead on the meridian, then I guess I could expect the Dec drift to

be only

> in Y. If I am away from the meridian, I seem to be seeing an X

component to

> the drift. I do not believe this is a rate error. I have been

pulling this

> drift out of the PE data I have been using, but do not fully

understand what

> I am seeing. Thoughts?

>

> Marty

>

>

> ----- Original Message -----

> From: "robert_alan_wright" alan@y...>

> To: Losmandy_users@y...>

> Sent: Saturday, April 20, 2002 1:06 PM

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

>

>

> > --- In Losmandy_users@y..., Rene Goerlich Rene@D...> wrote:

> > >

> > > What Alan writes (0.11 percent deviation from the tracking

rate)

> > > shows that the sky moves differently, only at the zenith you

have

> > > the exact sidereal rate. King tracking takes care of this.

> > > PEC is not meant to correct for different tracking rates

> > > in the sky caused by refraction.

> >

> > This is not correct for at least my case. My tracking is too

> > fast *at the meridian*. The data posted to the file section

> > of this group (for the new worm threads) shows the amount of

> > RA drift I get near the meridian. The graph, in particular,

> > makes it obvious. It doesn't seem as though the King rate

> > should help, since King and Sidereal should be the same near

> > the meridian. Correct? To the limited extent that I have tried

> > the (on-adaptive) King rate, it did not help at all.

> >

> > For me this is not too much of a problem. If I could guide at

> > all with my mount, I could guide this small drift out. However,

> > with many people reporting the same problem to differing degrees,

> > including people with vastly more expertise than myself, it is

> > annoying that you are so defensive about this. If you want to

> > claim (as Scott Losmandy said to me), that this is within the

> > manufacturting limits of the product, then do so, and let the

> > chips fall where they may.

> >

> > With the greatly improved worm gears that Losmandy will soon

> > apparently be shipping, this problem will become much more

> > glaring. When my PE was greater than 30 arcseconds, there was

> > no way I could notice this problem. But I saw it immediately

> > after the new worm was installed.

> >

> > > If you take a look at my website, you'll see that not only bugs

> > > were removed within the Levels, but even new features very

included.

> > > The latest L1 software images are available at my website for

> > > free download. L2 and L3 users can get their images from me and

> > > I offer to upgrade their EPROMs at a non-profit fee to let them

> > > take advantage of the latest development.

> >

> > I hope you are not implying that known bugs are left in level 1

> > in order to induce people to upgrade. For a $1500 system, holding

> > out for a few more bucks to get bug fixes is practically

criminal.

> > By the standards of the US software industry, you would have to

> > give away the upgrades if that was the only means you had to fix

> > known bugs.

> >

> > It amazes me that so many of the astronomy products I buy

> > have a mix of astoundingly good qualities and designs mixed

> > with egregious and unnecessary flaws. For example, my G11/Gemini

> > is generally a beautiful and finely crafted mount, yet does not

> > track well enough to make CCD images. Apparently the market is

> > not large enough (or is too forgiving) for appropriate pressures

> > to be applied to the producers. Some of the companies I have

bought

> > from, however, adhere to higher standards than others, and I will

> > definitely channel my future expenditures in those directions,

and

> > warn people away from products I have had trouble with. I only

wish

> > I had heeded some of the warnings I received before I made

certain

> > purchases.

> >

> > Alan

> >

> >

> >

> >

> > To unsubscribe from this group, send an email to:

> > Losmandy_users-unsubscribe@e...

> >

> >

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/

> >

> >

> >







----------------------------

#9730 Apr 20, 2002

robert_alan_wright wrote:

>

> I will be satisifed with this mount for a while if I can get

> it to guide well enough for CCD photos.

>



Alan,



I have been reading through this thread and have what is probably a very

naive

question regarding your statement.



Why is the guiding tolerance for CCD more critical than film ?



I am infering (incorrectly probably g>) that you are unable to image

with your

particular set-up. I have been able to image (film) on a mount that is

much worse

than a G-11 in tracking and so this prompts my asking for clarification.



Best Regards



Bill





I would much rather





--

William R. Mattil.| Fred Astaire wasn't so great.

wrmattil@....| Ginger had to do it all backwards

(972) 399-4106..| and... in high heels.



----------------------------

#9731 Apr 20, 2002

----- Original Message -----

From: "robert_alan_wright" alan@...>

Subject: [Losmandy_users] Re: Periodic Rate Too Fast...





"I will be satisifed with this mount for a while if I can get

it to guide well enough for CCD photos. I would much rather

hear from you about ways to improve my guiding than about

sidereal rates."



Have you looked at www.ccdtom.com? I don't know what camera you're

imaging with or which software you are using, but Tom Carrico has some tips

on his page about setting up and calibrating with an ST-7 and the G11

(w/Gemini) on his web page. You can also take a look at some of his recent

(and fairly long exposure images) using a Tak FS-102 on the G-11. He doesn't

seem to be having a whole lot of problems. FI, take a look at his M106 under

the Takahashi section. These are ten 10 minute exposures. And these were

done from his backyard in Corvallis on a tripod mounted G-11 w/Gemini and no

special tweaking of his mount. No extra bearings, no special setting.



Successful imaging is not just an issue of spending big bucks for a mount.

It involves an integrated system including camera, mount, OTA, mount

software, camera software, and probably a little bit of luck and black magic

g>. At ARGO, we have everything from G-11's to MI250, Paramounts, and

AP900's and 1200's. Some guys with G-11's get better results than some with

AP1200's, although the differences in quality are diminishing as we all get

more experience. And we've been at it out there for 5 years. Bill McLaughlin

has been at it since '93 or '94.



This aspect of the hobby (and for most of us it is still a hobby) will

challenge all who attempt it to the limits of their abilities. I'm neither a

hardware nor software engineer, but have benefited from having a group of

friends who have been able to show me tips and tricks along the way.



I don't know if you're trying to go it alone or have others you image with,

but if you don't, I would highly recommend it. It will definitely save you a

lot of time and grief.





Jim Girard

home.teleport.com/~argo



----------------------------

#9732 Apr 20, 2002

--- In Losmandy_users@y..., "Jim Girard" argo@t...> wrote: > ----- Original Message -----

> From: "robert_alan_wright" alan@y...>

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

>

>

> "I will be satisifed with this mount for a while if I can get

> it to guide well enough for CCD photos. I would much rather

> hear from you about ways to improve my guiding than about

> sidereal rates."

>

> Have you looked at www.ccdtom.com? I don't know what camera

you're > imaging with or which software you are using, but Tom Carrico has

some tips > on his page about setting up and calibrating with an ST-7 and the

G11 > (w/Gemini) on his web page. You can also take a look at some of his

recent > (and fairly long exposure images) using a Tak FS-102 on the G-11.



Thanks for the pointer. I have almost the same equipment,

coincidentally, so this should be useful to me.

> He doesn't

> seem to be having a whole lot of problems. FI, take a look at his

M106 under > the Takahashi section. These are ten 10 minute exposures. And these

were > done from his backyard in Corvallis on a tripod mounted G-11

w/Gemini and no > special tweaking of his mount. No extra bearings, no special

setting. >

> Successful imaging is not just an issue of spending big bucks for a

mount. > It involves an integrated system including camera, mount, OTA, mount

> software, camera software, and probably a little bit of luck and

black magic > g>. At ARGO, we have everything from G-11's to MI250, Paramounts,

and > AP900's and 1200's. Some guys with G-11's get better results than

some with > AP1200's, although the differences in quality are diminishing as we

all get > more experience. And we've been at it out there for 5 years. Bill

McLaughlin > has been at it since '93 or '94.



It seems to me that most of it is purely a matter of

properly functioning hardware and software. I don't

participate in the guiding, I just watch to see if

it works. All I have to do is set things up right.

How many things are there to do differently? Not many.



To the limited extent that there are skills involved, I don't

think these are big secrets. I am still learning a few small

things here and there, but nothing startling. What are all

these areas where skill matters so much?



Based on related opinions that I get from others, I think the

the mounts do matter quite a lot. If your guider cannot keep

up with what your mount throws at it, then you cannot get good

photos.

> This aspect of the hobby (and for most of us it is still a hobby)

will > challenge all who attempt it to the limits of their abilities. I'm

neither a > hardware nor software engineer, but have benefited from having a

group of > friends who have been able to show me tips and tricks along the way.



I've read books full of these tips and tricks, and there really

just isn't that much there. Pretty soon technology will be the

dominant factor in successful astrophotography, if it isn't

already.



Of the problems I have corrected in the past, they have all

been: complete failure of the equipment, incompatibility of

two pieces of equipment, or limitations in the performance

of the equipment. I have solved all of these by changing

equipment. I can't think of any problems I've solved in which

learning some special secret allowed me to get past it.



Maybe when I graduate to taking very long guided photos there

will be more to know about the behavior of mounts over these

longer periods of time. However, I'm still trying to get past

the first turn of the gears.

> I don't know if you're trying to go it alone or have others you

image with, > but if you don't, I would highly recommend it. It will definitely

save you a > lot of time and grief.



I rely heavily on these groups to help me out. Perhaps too

heavily, as people are getting tired of hearing from me.

I don't have time to participate in the local Astronomy

clubs, so I'll have to make do with what I learn here and

from publications.



I would be nice to see if a more experienced person could

get better results than I am with my equipment. If so, I

would know the trick within the first 5 minutes and move on.

If there are such tricks or techniques, it seems like I should

be able to learn these from the group. And I wonder why

Ron Wodaski left all the good stuff out of his book?

(Just kidding Ron, it's a great book).



Alan







----------------------------

#9735 Apr 20, 2002

> It seems to me that most of it is purely a matter of

> properly functioning hardware and software. I don't

> participate in the guiding, I just watch to see if

> it works. All I have to do is set things up right.

> How many things are there to do differently? Not many.

>

> To the limited extent that there are skills involved, I don't

> think these are big secrets. I am still learning a few small

> things here and there, but nothing startling. What are all

> these areas where skill matters so much?



It may not be skill, but it is knowledge. I have been imaging for about 6

years, with what most would consider good mounts -AP800, G-11, Tak EM-10 and

MI-250. All of them require a learning curve that is also a function of the

telescope and camera used. It is naive to assume that you just bolt

everything together and it will work. I image at a site where there are 5 of

us that share learnings about our experiences in imaging. Guiding is almost

always the #1 topic. There are so many variables to consider, and they are

very intereactive - Guiding exposure, minimum move, maximum move, backlash,

delay between exposure, disabling dec corrections, balance, guide star

brightness, object elevation, polar alignment, cable management, camera

temperature and so on.

3 years ago, I kept about 50% of my images, today more than 80%. The best

imagers I know do not keep all of thier images. There are just too many

things to go wrong. Even if you spend $10,000 on a mount. Every year, I

learn more things about how to get better tracking. You just have to be

patient. With the G-11, it took one summer to figure out how to make it work

to keep about 80% of my images. With the Gemini, the percentage has

increased, but I am not exactly sure why. Perhaps it is the servo vs stepper

motors. A big help is the feature in Maxim 3.0 to disable dec correction in

one direction. Now I never have to worry about backlash in dec, or the mount

oscillating in dec causing issues in RA.

I guess what I am saying is that the G-11 is a fine mount and can be made to

work very well. Also, spending 5X on another mount is no guarantee that you

will get great results. You just have to be patient and learn how everything

works together.



I highly recommend the G-11 and Gemini, not just because they are great

products, but because of the outstanding support of Scott and Rene.



Tom Carrico

www.ccdtom.com













---------------

Do You Yahoo!?

Get your free @... address at mail.yahoo.com



----------------------------

#9737 Apr 20, 2002

--- In Losmandy_users@y..., "Tom Carrico" tom@c...> wrote: > >

> > It seems to me that most of it is purely a matter of

> > properly functioning hardware and software. I don't

> > participate in the guiding, I just watch to see if

> > it works. All I have to do is set things up right.

> > How many things are there to do differently? Not many.

> >

> > To the limited extent that there are skills involved, I don't

> > think these are big secrets. I am still learning a few small

> > things here and there, but nothing startling. What are all

> > these areas where skill matters so much?

>

> It may not be skill, but it is knowledge. I have been imaging for

about 6 > years, with what most would consider good mounts -AP800, G-11, Tak

EM-10 and > MI-250. All of them require a learning curve that is also a

function of the > telescope and camera used. It is naive to assume that you just bolt

> everything together and it will work. I image at a site where

there are 5 of > us that share learnings about our experiences in imaging. Guiding

is almost > always the #1 topic. There are so many variables to consider, and

they are > very intereactive - Guiding exposure, minimum move, maximum move,

backlash, > delay between exposure, disabling dec corrections, balance, guide

star > brightness, object elevation, polar alignment, cable management,

camera > temperature and so on.

> 3 years ago, I kept about 50% of my images, today more than 80%.

The best > imagers I know do not keep all of thier images. There are just too

many > things to go wrong. Even if you spend $10,000 on a mount. Every

year, I > learn more things about how to get better tracking. You just have

to be > patient. With the G-11, it took one summer to figure out how to

make it work > to keep about 80% of my images. With the Gemini, the percentage has

> increased, but I am not exactly sure why. Perhaps it is the servo

vs stepper > motors. A big help is the feature in Maxim 3.0 to disable dec

correction in > one direction. Now I never have to worry about backlash in dec, or

the mount > oscillating in dec causing issues in RA.

> I guess what I am saying is that the G-11 is a fine mount and can

be made to > work very well. Also, spending 5X on another mount is no guarantee

that you > will get great results. You just have to be patient and learn how

everything > works together.

>

> I highly recommend the G-11 and Gemini, not just because they are

great > products, but because of the outstanding support of Scott and Rene.

>

> Tom Carrico

> www.ccdtom.com



I'm still waiting to hear what all this magical knowledge is.

I spent a year reading books, articles, and discussion groups

before I made the plunge into CCD photography. All of the things

you mention above are pretty obvious, and are easy to play around

with. I have done so extensively, and still have a long list of

additional things to try. Maybe my results will improve at some

point, but so far they are not good enough to be worth the time

and money.



I would add that I have gotten very good and generous support

from Scott. He replaced the bad gears in my G11, and sent me

an optocoupler at no charge when my SBIG relay box would not

work with the Gemini. However, I've also gotten broken products

from him, including two DOA Gemini's before my current one.

I sent back a fine MI-250 mount because of those two broken

Gemini's, not knowing at the time that the problem was a

common one with Gemini. I learned that on this group after

I got my G11.



As for Rene, I've gotten nothing but defensiveness and

character assassination. And today I find out you have

to pay him for upgrades to get bug fixes. What a racket!



Alan







----------------------------

#9738 Apr 20, 2002

Hi Scott,



In my case, the test that finally made me wonder if there was something that I could do was a 20 minute PE logging run of the new worm... Where the total amount of drift was 59.8 arcseconds... That is equal to about 179.4 per hour... I should also not that I made 5 other PE logging runs that same night that ranged from 8 to 12 minutes... All of which covered over an hour. All showed the same drift rate. The measurements were taken at about 15. - 30. east of the meridian and at +0.45' Dec. I am approximately at 42.5. Lat. Things I cannot totally rule out are flexure and mirror flop, although I would expect to see the drift rate change in stead of being constant. I would expect at least some component to show up as drift in dec and there was very little. What dec drift there was, was most likely due to polar alignment issues.

This whole thing is something that I can live with, As I use my ST-4 to guide with anytime I photograph, I'm just wondering if there is a simple solution (Read: Adjustment).



Thanks

Frank

www.my-spot.com ----- Original Message -----

From: losmandy

To: Losmandy_users@yahoogroups.com

Sent: Saturday, April 20, 2002 2:12 PM

Subject: [Losmandy_users] Re: Periodic Rate Too Fast...



My question is were the above tests run for a full hour or are they a

calculated hour?





Thank you,

Scott





[Non-text portions of this message have been removed]



----------------------------

#9741 Apr 20, 2002

Frank,



Any chance you could upload this data you are talking about.



I'd like to get a peek at what all the hub-bub is about.



Camera used and FL would be nice to know as well as where

in the sky the data was gathered.



How would I recognize this drift?



If you just want to send it to me via PEM that's OK too or

even if you don't send it all that's OK too. I'm not trying

to prove you wrong or anything. Just want to understand what

people are talking about.



Regards,

--- In Losmandy_users@y..., "Franklin A. Holub" lists@m...> wrote:

> Hi Scott,

>

> In my case, the test that finally made me wonder if there was

something that I could do was a 20 minute PE logging run of the new

worm... Where the total amount of drift was 59.8 arcseconds... That

is equal to about 179.4 per hour... I should also not that I made 5

other PE logging runs that same night that ranged from 8 to 12

minutes... All of which covered over an hour. All showed the same

drift rate. The measurements were taken at about 15. - 30. east of

the meridian and at +0.45' Dec. I am approximately at 42.5. Lat.

Things I cannot totally rule out are flexure and mirror flop,

although I would expect to see the drift rate change in stead of

being constant. I would expect at least some component to show up as

drift in dec and there was very little. What dec drift there was,

was most likely due to polar alignment issues.

> This whole thing is something that I can live with, As I use my ST-

4 to guide with anytime I photograph, I'm just wondering if there is

a simple solution (Read: Adjustment).

>

> Thanks

> Frank

> www.my-spot.com

> ----- Original Message -----

> From: losmandy

> To: Losmandy_users@y...

> Sent: Saturday, April 20, 2002 2:12 PM

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

>

> My question is were the above tests run for a full hour or are

they a

> calculated hour?

>

>

> Thank you,

> Scott

>

>

> [Non-text portions of this message have been removed]



----------------------------

#9742 Apr 20, 2002

Whoa!!! After reading all these flames I'm sorry I posted this!!! YIKES!!!



Let me SIMPLIFY my question and wrestle my thread back G>...



On the normal stepper (non-Gemini) "Digital Drive" system, is there ANY way to fine tune the sidereal rate (besides King)?





Be Nice to each other,

Frank

www.my-spot.com ----- Original Message -----

From: Franklin A. Holub

To: Losmandy_users@yahoogroups.com

Sent: Saturday, April 20, 2002 8:48 PM

Subject: Re: [Losmandy_users] Re: Periodic Rate Too Fast...





Hi Scott,



In my case, the test that finally made me wonder if there was something that I could do was a 20 minute PE logging run of the new worm... Where the total amount of drift was 59.8 arcseconds... That is equal to about 179.4 per hour... I should also not that I made 5 other PE logging runs that same night that ranged from 8 to 12 minutes... All of which covered over an hour. All showed the same drift rate. The measurements were taken at about 15. - 30. east of the meridian and at +0.45' Dec. I am approximately at 42.5. Lat. Things I cannot totally rule out are flexure and mirror flop, although I would expect to see the drift rate change in stead of being constant. I would expect at least some component to show up as drift in dec and there was very little. What dec drift there was, was most likely due to polar alignment issues.

This whole thing is something that I can live with, As I use my ST-4 to guide with anytime I photograph, I'm just wondering if there is a simple solution (Read: Adjustment).



Thanks

Frank

www.my-spot.com

----- Original Message -----

From: losmandy

To: Losmandy_users@yahoogroups.com

Sent: Saturday, April 20, 2002 2:12 PM

Subject: [Losmandy_users] Re: Periodic Rate Too Fast...



My question is were the above tests run for a full hour or are they a

calculated hour?





Thank you,

Scott





[Non-text portions of this message have been removed]





Yahoo! Groups Sponsor

ADVERTISEMENT









To unsubscribe from this group, send an email to:

Losmandy_users-unsubscribe@egroups.com







Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.





[Non-text portions of this message have been removed]







----------------------------

#9743 Apr 20, 2002

I don't know Frank.



Has been pretty tame so far.



You should hang-out on the alt.flame newsgroup

for about 5 seconds (that's all I could take :)



There is more going on here than your post.



So, how about that data?



Regards,

--- In Losmandy_users@y..., "Franklin A. Holub" lists@m...> wrote:

> Whoa!!! After reading all these flames I'm sorry I posted this!!!

YIKES!!!

>

> Let me SIMPLIFY my question and wrestle my thread back G>...

>

> On the normal stepper (non-Gemini) "Digital Drive" system, is

there ANY way to fine tune the sidereal rate (besides King)?

>

>

> Be Nice to each other,

> Frank

> www.my-spot.com

> ----- Original Message -----

> From: Franklin A. Holub

> To: Losmandy_users@y...

> Sent: Saturday, April 20, 2002 8:48 PM

> Subject: Re: [Losmandy_users] Re: Periodic Rate Too Fast...

>

>

> Hi Scott,

>

> In my case, the test that finally made me wonder if there was

something that I could do was a 20 minute PE logging run of the new

worm... Where the total amount of drift was 59.8 arcseconds... That

is equal to about 179.4 per hour... I should also not that I made 5

other PE logging runs that same night that ranged from 8 to 12

minutes... All of which covered over an hour. All showed the same

drift rate. The measurements were taken at about 15. - 30. east of

the meridian and at +0.45' Dec. I am approximately at 42.5. Lat.

Things I cannot totally rule out are flexure and mirror flop,

although I would expect to see the drift rate change in stead of

being constant. I would expect at least some component to show up as

drift in dec and there was very little. What dec drift there was,

was most likely due to polar alignment issues.

> This whole thing is something that I can live with, As I use my

ST-4 to guide with anytime I photograph, I'm just wondering if there

is a simple solution (Read: Adjustment).

>

> Thanks

> Frank

> www.my-spot.com

> ----- Original Message -----

> From: losmandy

> To: Losmandy_users@y...

> Sent: Saturday, April 20, 2002 2:12 PM

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

>

> My question is were the above tests run for a full hour or are

they a

> calculated hour?

>

>

> Thank you,

> Scott

>

>

> [Non-text portions of this message have been removed]

>

>

> Yahoo! Groups Sponsor

> ADVERTISEMENT

>

>

>

>

> To unsubscribe from this group, send an email to:

> Losmandy_users-unsubscribe@e...

>

>

>

> Your use of Yahoo! Groups is subject to the Yahoo! Terms of

Service.

>

>

> [Non-text portions of this message have been removed]



----------------------------

#9746 Apr 21, 2002

Frank,

> Any chance you could upload this data you are talking about.

> I'd like to get a peek at what all the hub-bub is about.

> Camera used and FL would be nice to know as well as where

> in the sky the data was gathered.

> How would I recognize this drift?

> If you just want to send it to me via PEM that's OK too or

> even if you don't send it all that's OK too. I'm not trying

> to prove you wrong or anything. Just want to understand what

> people are talking about.

>

> Regards,

>

> --- In Losmandy_users@y..., "Franklin A. Holub" lists@m...> wrote:

> > Hi Scott,

> >

> > In my case, the test that finally made me wonder if there was

> something that I could do was a 20 minute PE logging run of the new

> worm... Where the total amount of drift was 59.8 arcseconds... That

> is equal to about 179.4 per hour... I should also not that I made 5

> other PE logging runs that same night that ranged from 8 to 12

> minutes... All of which covered over an hour. All showed the same

> drift rate. The measurements were taken at about 15. - 30. east of

> the meridian and at +0.45' Dec. I am approximately at 42.5. Lat.

> Things I cannot totally rule out are flexure and mirror flop,

> although I would expect to see the drift rate change in stead of

> being constant. I would expect at least some component to show up as

> drift in dec and there was very little. What dec drift there was,

> was most likely due to polar alignment issues.

> This whole thing is something that I can live with, As I use my ST-

> 4 to guide with anytime I photograph, I'm just wondering if there is

> a simple solution (Read: Adjustment).

>

> Thanks

> Frank

> www.my-spot.com

> ----- Original Message -----

> From: losmandy

> To: Losmandy_users@y...

> Sent: Saturday, April 20, 2002 2:12 PM

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

>

> My question is were the above tests run for a full hour or are

> they a calculated hour?

Let me make a few 'points' about this problem.

Firstly, changing a worm can't alter the gear ratio (so this can be ruled

out). Assuming the worm has the same number of 'starts' as the original

(and you cannot change this without changing the tooth form on the main

gear), you get the same advance for each turn of the worm. So the fact

that the problem was found above after trying the new worm, is in this

context irrelevant.

Now the system comprises a servo motor (or stepper motor), driving a

gearbox, whose ratio is known. Rene, is simply making the point, that

given the gear ratio, there is a 'correct' speed to drive the motor, and

changing from this is silly.

Polar misalignment _will_ cause a small error in RA rate, but the effect

is tiny, certainly less than the figures above (which correspond to about

a 0.3% error). This error is also significantly more than can be accounted

for by a normal crystal error (though it would be worth asking if the

problem was only seen in an 'extreme' temperature enviroment).

If the fault only appeared with the Gemini controller, it could be being

'created' in various ways. For instance if multiple alignment stars have

been used, and the alignment was inaccurate, the 'modelling' used inside

the Gemini, will try to correct for any error in the angle between the

stars, and give a variable drive rate across the section of the sky. Hence

when testing for this fault, only a single star alignment should be used.

However since the same fault has been mentioned with reference to the

'stepper' drive system, this also can be ruled out.

I do find myself wondering if the fault is actually being generated by

something 'spurious'. For instance if the guide cable was getting some

'pickup' from another source, and the Gemini was seeing a 'pulse' of guide

correction every few seconds, it could give this behaviour. Also if the

scope was significantly unbalanced, and the clutch was 'creeping' a

little, a similar effect could be seen.

The 'error', could most easily be seen, given it's size, by the simple

expedient of removing all guide correction, by disconnecting the cable at

the Gemini end (to avoid the possibility that the cable was inducing

anything), and letting the scope run 'unguided' for a period like an hour,

and using a crosshair eyepiece, see if the target has moved at all.

I have to say, that I have not seen any such error on my G11, with the

latest ROMs for the Gemini (Level 2 V1.2), being able to leave it

unguided, and then return after a coffee break, with the star that was

last used, still happily sitting in the crosshairs (after a really _good_

polar alignment...). I cannot remember seeing any such problem with the

older ROMs either. My only 'fault' with the mount, is the PEC, which is

'as expected', but I would love to see reduced. I am watching the new

worms with real interest in this regard. :-)

The 'lovely' thing about this system, is that both the mechanical, end

electronic designers are 'present', and I am sure that the reason will

eventually be found.



Best Wishes







----------------------------

#9748 Apr 21, 2002

Interestingly, A year or so ago, in an attempt to fully understand the effects of polar misalignment, I made a CAD model of a EQ mounted "telescope" tube and polar axis with a "guide star" in a mechanical simulation package. In this model, polar misalignment only revealed itself through the scope as drift in Dec... If I can find the model, I'll post an AVI of the simulation.



Frank

www.my-spot.com ----- Original Message -----

From: Roger Hamlett

To: Losmandy_users@yahoogroups.com

Sent: Sunday, April 21, 2002 4:58 AM

Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

Polar misalignment _will_ cause a small error in RA rate, but the effect

is tiny, certainly less than the figures above (which correspond to about

a 0.3% error). This error is also significantly more than can be accounted

for by a normal crystal error (though it would be worth asking if the

problem was only seen in an 'extreme' temperature enviroment).



[Non-text portions of this message have been removed]



----------------------------

#9755 Apr 21, 2002

Scott,



Now you are back: Are the changes to the new worm going to be applied to the

HGM200?



I have to admit when I tested the PE recently it was whole +/- 4 arcsecs,

with no big peaks, so it really is not a problem, just wonderin'.



Can I also add that the support from yourself and Rene is very welcome and

keeps customers (happy). For example, once you realise the huge number of

lines of code in the ROM and the fact that we are getting upgrades (more

features) for a cheap (and I do mean cheap) cost then we should encourage

Rene in his endeavors. So variable rate tracking would be most welcome as

would......... The PC control software for example costs a huge NOTHING

and is a great interface.



Also, I am not too sure where the competetitor to the G11 (at the same

cost) is. Yes, there are better mounts, but not with the same performance

and cost. Especially with the same sheer engineering effort and damn good

looks. I showed one of the components from my GM8 to an engineer friend and

he did not understand why you bothered to machine it from aluminum when a

cheaper alternative could be used. Because....



And when you go to super mounts the HGM200 takes some beating. Remer, I am

on the other side of the pond and I pay $1.5 to every one of your dollars

and they still are good value.



Hopefully, I will soon be able to try out some real CCD imaging now that I

have a J. Lacey Optocoupler for my ST7.



Keep up the good work guys.





G Sallit

www.sallit.freeserve.co.uk



----------------------------

#9784 Apr 22, 2002

Interestingly, A year or so ago, in an attempt to fully understand

> the effects of polar misalignment, I made a CAD model of a EQ

> polar misalignment only revealed itself through the scope as drift

> in Dec... If I can find the model, I'll post an AVI of the simulation.

>

> Frank

> www.my-spot.com

> ----- Original Message -----

> From: Roger Hamlett

> To: Losmandy_users@yahoogroups.com

> Sent: Sunday, April 21, 2002 4:58 AM

> Subject: [Losmandy_users] Re: Periodic Rate Too Fast...

> Polar misalignment _will_ cause a small error in RA rate, but the

effect > is tiny, certainly less than the figures above (which correspond to

about > a 0.3% error). This error is also significantly more than can be

accounted > for by a normal crystal error (though it would be worth asking if the

> problem was only seen in an 'extreme' temperature enviroment).

When I say 'small', I mean _small_... :-)

The effect in RA, is exactly the same as if you tilt two circles, rotate

them together, and look at the RA angular motion from a point that is

directly below one of the circles. At the meridian, there will be no

difference, but there will be a slight change in the perceived motion at

other angles, but for normal 'error' angles, I doubt if it is even

measurable. The major motion is as you say perpendicular to the circles

(hence in Dec), but there has to be a very slight acceleration and

decelleration in RA as well. The error would be at least an order of

magnitude below the perceived error, for any 'normal' error angle.



Best Wishes



----------------------------

#9797 Apr 22, 2002

Frank wrote: > With all of this worm gear testing, I find that my G-11 runs too fast

> by 179.5 arcseconds per hour. For testing I removed this error from

> the PE in excel. It did limit my test to 4 or 5 cycles before the

> guide star left the tracking box. This is NOT new to the new worm

> gear. It seems to happen no matter which of my 5 worms are in the RA

> drive.



Geez, Frank,...5 worm gears???



That's one variable I was albel to eliminate from my testing early on. Using my "big" CCD (HX916) instead of the guider, I noted a star centroid location and took an image every 2 minutes for about 4 hours. The star wandered around the centroid location due to PE, but wasn't measurably fast or slow.

> Anyway, Is there an adjustment or some other way to tweak the drive

> rate a bit closer to perfect (without using PEC)?



I would think there should be a "pot" on the control board to control the quartz oscillator frequency...probably going to have to get Scott in on this one. Good luck!



Paul







Contact Us
This Site's Privacy Policy
Google's privacy policies

S
e
n
i
o
r
T
u
b
e
.
o
r
g